Typical inductors may include toroidal cores and shaped-cores, including a shield core and drum core, U core and I core, E core and I core, and other matching shapes. The typical core materials for these inductors are ferrite or normal powder core materials, which include iron (Fe), Sendust (Al—Si—Fe), MPP (Mo—Ni—Fe), and HighFlux (Ni—Fe). The inductors typically have a conductive winding wrapped around the core, which may include, but is not limited to a magnet wire coil that may be flat or rounded, a stamped copper foil, or a clip. The coil may be wound on the drum core or other bobbin core directly. Each end of the winding may be referred to as a lead and is used for coupling the inductor to an electrical circuit. The winding may be preformed, semi-preformed, or non-preformed depending upon the application requirements. Discrete cores may be bound together through an adhesive.
With the trend of power inductors going toward higher current, a need exists for providing inductors having more flexible form factors, more robust configurations, higher power and energy densities, higher efficiencies, and tighter inductance and Direct Current Resistance (“DCR”) tolerance. DC to DC converters and Voltage Regulator Modules (“VRM”) applications often require inductors having tighter DCR tolerances, which is currently difficult to provide due to the finished goods manufacturing process. Existing solutions for providing higher saturation current and tighter tolerance DCR in typical inductors have become very difficult and costly and do not provide the best performance from these typical inductors. Accordingly, the current inductors are in need for such improvements.
To improve certain inductor characteristics, toroidal cores have recently been manufactured using an amorphous powder material for the core material. Toroidal cores require a coil, or winding, to be wound onto the core directly. During this winding process, the cores may crack very easily, thereby causing the manufacturing process to be difficult and more costly for its use in surface-mount technology. Additionally, due to the uneven coil winding and coil tension variations in toroidal cores, the DCR is not very consistent, which is typically required in DC to DC converters and VRM. Due to the high pressures involved during the pressing process, it has not been possible to manufacture shaped-cores using amorphous powder materials.
Due to advancements in electronic packaging, the trend has been to manufacture power inductors having miniature structures. Thus, the core structure must have lower and lower profiles so that they may be accommodated by the modem electronic devices, some of which may be slim or have a very thin profile. Manufacturing inductors having a low profile has caused manufactures to encounter many difficulties, thereby making the manufacturing process expensive.
For example, as the components become smaller and smaller, difficulty has arisen due to the nature of the components being hand wound. These hand wound components provide for inconsistencies in the product themselves. Another encountered difficulty includes the shape-cores being very fragile and prone to core cracking throughout the manufacturing process. An additional difficulty is that the inductance is not consistent due to the gap deviation between the two discrete cores, including but not limited to drum cores and shielded cores, ER cores and I cores, and U cores and I cores, during assembly. A further difficulty is that the DCR is not consistent due to uneven winding and tension during the winding process. These difficulties represent examples of just a few of the many difficulties encountered while attempting to manufacture inductors having a miniature structure.
Manufacturing processes for inductors, like other components, have been scrutinized as a way to reduce costs in the highly competitive electronics manufacturing business. Reduction of manufacturing costs is particularly desirable when the components being manufactured are low cost, high volume components. In a high volume component, any reduction in manufacturing cost is, of course, significant. It may be possible that one material used in manufacturing may have a higher cost than another material. However, the overall manufacturing cost may be less by using the more costly material because the reliability and consistency of the product in the manufacturing process is greater than the reliability and consistency of the same product manufactured with the less costly material. Thus, a greater number of actual manufactured products may be sold, rather than being discarded. Additionally, it also is possible that one material used in manufacturing a component may have a higher cost than another material, but the labor savings more than compensates for the increase in material costs. These examples are just a few of the many ways for reducing manufacturing costs.
It has become desirable to provide a magnetic component having a core and winding configuration that can allow one or more of the following improvements, a more flexible form factor, a more robust configuration, a higher power and energy density, a higher efficiency, a wider operating frequency range, a wider operating temperature range, a higher saturation flux density, a higher effective permeability, and a tighter inductance and DCR tolerance, without substantially increasing the size of the components and occupying an undue amount of space, especially when used on circuit board applications. It also has become desirable to provide a magnetic component having a core and winding configuration that can allow low cost manufacturing and achieves more consistent electrical and mechanical properties. Furthermore, it is desirable to provide a magnetic component that tightly controls the DCR over large production lot sizes.